1. Field of the Invention
This invention relates to a transparency, e.g. a window, having sensors responsive to property changes of the transparency, e.g. responsive to chemical changes, physical impact and/or electrical changes, and more particularly, to an aircraft or aerospace window, e.g. an aircraft windshield having sensors to monitor the real time performance of features, properties, or characteristics of accessories that provide the windshield with visual acuity.
2. Discussion of the Presently Available Transparency Technology
Aircraft or aerospace windows, e.g. aircraft windshields include a laminate of plastic layers or sheets, glass layers or sheets and combinations thereof. The layers of an inner segment of the windshield face the interior of the aircraft and provide structural stability to the windshield. The outer segment of the windshield faces the exterior of the aircraft and usually includes a laminate of glass sheets. The outer segment of the windshield, which can also provide structural stability is usually provided with accessories for visual acuity. For example and not limiting to the discussion, the accessories can included an electrically conductive coating, or a plurality of electrically conductive wires, between and connected to a pair of spaced bus bars to heat the windshield to prevent the formation of, and/or remove fog and ice on and/or from, respectively, the outer surface of the windshield.
As is appreciated by those skilled in the art, as the service time of the aircraft windshield increases, the operating efficiency of the windshield decreases until such time that the accessories of the windshield become non-functional, and the windshield needs to be replaced or repaired. More particularly, the peripheral edge of the windshield has an outboard moisture seal that is a barrier to prevent moisture from entering between the plastic and glass layers or sheets of the windshield. When the seal fails, e.g. cracks and/or the layers de-bond due to erosion caused by wind and rain, moisture enters between the layers of the windshield. While the cracking or de-bonding of the seal is not a structural issue, when moisture reaches inside the windshield, the windshield can de-laminate, and the conductive coating or wires, whichever is present can be damaged and fail, thereby reducing the service life of the windshield. More particularly, when delamination of the windshield occurs, increased amounts of moisture move between the layers of the windshield accelerating the degradation of the windshield, e.g. damage and/or failure of the bus bars and electrically conductive coating or wires reducing or eliminating the defrosting capabilities of the windshield.
Untimely response to repair defects in the accessories of the transparency when they begin, decreases the operating efficiency of the transparency and can result in the need for emergency maintenance, e.g. transparency repair or replacement. It would be advantageous, therefore, to provide a transparency having sensors to monitor the performance of the transparency so that the repair, or replacement, of the transparency is scheduled maintenance and not emergency maintenance.